Field of the Invention
The present invention relates to a cutting apparatus, and more particularly to a cutting apparatus provided with rotary dressing means.
Description of the Related Art
Cutting apparatus that cut a workpiece such as a wafer with a cutting blade rotating at a high speed are likely to suffer a problem in that as the cutting of the workpiece continues, the cutting blade has its tip end tapered off, and when the workpiece is continuously cut by the tapered-off tip end of the cutting blade, the shape accuracy of the side faces of device chips cut off the workpiece tends to be lowered. In order to prevent the problem from occurring, it is necessary to dress the cutting blade by having the tip end thereof cut into a dressing grindstone and worn thereby. The dressing process serves to true the cutting blade which is mounted off center on a spindle and also to sharpen the cutting blade which has been glazed or loaded by the cutting process.
The dressing process of the cutting blade needs to be carried out at appropriate times during the cutting process. Usually, after the workpiece has been removed from the chuck table, a dedicated dressing board is held under suction on the chuck table, and the cutting blade is dressed by the dressing board. However, since the steps of holding the dressing board under suction on the chuck table and removing the dressing board from the chuck table are very complex, it has been customary to provide an auxiliary chuck table dedicated for use with the dressing board in the vicinity of the chuck table (see Japanese Patent Laid-Open No. 2010-87122).
If the cutting apparatus has a highly hard cutting blade, then when the cutting blade is dressed by the dressing board held on the auxiliary chuck table dedicated for use with the dressing board, the amount of material cut off the dressing board by the cutting blade may not be sufficient. One solution is to use a rotary dressing device for dressing the cutting blade with a rotating dressing grindstone in order to increase the resistance with which to cut the rotating dressing grindstone.